% Plot_C5_inverter.m

clearvars; close all; clc;

addpath('../../HspiceToolbox')
x = loadsig('./spiceout/C5_inverter_VTC_ngsp_bin.raw');

lssig(x)

vin = evalsig(x,'VOLTAGE');
vout = evalsig(x, 'out');
dvout = evalsig(x, 'dvout');

Vdd = max(vin);
Vo_mid = Vdd/2;

figure(1)
plot(vin,vin, 'linewidth',2);
hold;
plot(vin,vout, 'linewidth',2);
set(gca, 'Fontsize',14);
title('Inverter: Voltage Transfer Characteristic');
xlabel('V_{in} (V)');
ylim([0 5])
xlim([0 5])
ylabel('V_{out} (V)');

% extract the values of the VTC parameters from the plots
first_idx = find(dvout <= -1, 1, 'first');
VOH = vout(first_idx);
VIL = vin(first_idx);
second_idx = find(dvout <= -1, 1, 'last');
VOL = vout(second_idx);
VIH = vin(second_idx);
mid_idx = find(vout <= Vo_mid, 1, 'first');
VSW = vout(mid_idx);
fprintf("VTC parameters extracted from the VTC curve:\n");
fprintf("\tVSW = %.4g (V)\n", VSW);
fprintf("\tVIL = %.4g (V)\n", VIL);
fprintf("\tVIH = %.4g (V)\n", VIH);
fprintf("\tVOL = %.4g (V)\n", VOL);
fprintf("\tVOH = %.4g (V)\n", VOH);

% back annotate the VTC parameters on the plots
str_vsw = sprintf("VSW = %.4g V", VSW);
text(2.6, 2.4, str_vsw, 'fontsize', 14)
p = plot(vin(mid_idx),vout(mid_idx),'s','MarkerFaceColor','blue', ...
    'MarkerSize',12);
str_vil = sprintf("VIL = %.4g V", VIL);
str_voh = sprintf("VOH = %.4g V", VOH);
text(2.3, 4.5, str_vil, 'fontsize', 14)
text(2.3, 4.2, str_voh, 'fontsize', 14)
p = plot(vin(first_idx),vout(first_idx),'s','MarkerFaceColor','black', ...
    'MarkerSize',12);
str_vih = sprintf("VIH = %.4g V", VIH);
str_vol = sprintf("VOL = %.4g V", VOL);
text(3, 1, str_vol, 'fontsize', 14)
text(3, 0.7, str_vih, 'fontsize', 14)
p = plot(vin(second_idx),vout(second_idx),'s','MarkerFaceColor','magenta', ...
    'MarkerSize',12);

legend('Vin','Vout', 'VSW','VIL & VOH', 'VIH & VOL','location','best');

% extract the VTC parameters directly from NGSPICE
vsw_ngsp = evalsig(x, 'vsw');
vil_ngsp = evalsig(x, 'vil');
vih_ngsp = evalsig(x, 'vih');
voh_ngsp = evalsig(x, 'voh');
vol_ngsp = evalsig(x, 'vol');
VSW_SPICE = vsw_ngsp(1);
VIL_SPICE = vil_ngsp(1);
VIH_SPICE = vih_ngsp(1);
VOL_SPICE = vol_ngsp(1);
VOH_SPICE = voh_ngsp(1);

fprintf("VTC parameters extracted directly from SPICE:\n");
fprintf("\tVSW = %.4g (V)\n", VSW_SPICE);
fprintf("\tVIL = %.4g (V)\n", VIL_SPICE);
fprintf("\tVIH = %.4g (V)\n", VIH_SPICE);
fprintf("\tVOL = %.4g (V)\n", VOL_SPICE);
fprintf("\tVOH = %.4g (V)\n", VOH_SPICE);

figure(2)
plot(vin,dvout, 'linewidth',2);
set(gca, 'Fontsize',14);
title('\textbf{\emph {Inverter DC gain:} \boldmath $dv_{out} \over dv_{in} $}',...
    'interpreter', 'latex','Fontsize',16); % \emph makes the text italics
% alternative syntax
%hT = title('\boldmath \textbf {Inverter DC gain} ( $\frac {dv_{out}} {dv_{in}}$ )','interpreter','latex');
%set(hT,'fontsize',20)
xlabel('V_{in} (V)');
ylabel('DC gain (V/V)')
xlim([0 5])

% careful the gain is negative! (inverting amplifier)
idx  = find(dvout==min(dvout));
gain = abs(dvout(idx));
VIN  = vin(idx);  % DC bias at the in node to get max gain
VOUT = vout(idx); % DC at the out node
fprintf("\nThe inverter max gain is %.4g (V/V)\n", gain);
fprintf("and it requires to bias the input node at: %.4g V DC\n",VIN);
str_gain = sprintf("|DC gain| = %.4g V/V", gain);
str_VIN = sprintf("VIN DC bias = %.4f V", VIN);
hold;
p = plot(vin(idx),dvout(idx),'-o','MarkerFaceColor',[1 0.5 0], ...
    'MarkerSize',12);
text(2.6, -gain+0.4, str_gain, 'fontsize', 14)
text(2.6, -gain-0.5, str_VIN, 'fontsize', 14)

x = loadsig('./spiceout/C5_inverter_TRAN_ngsp_bin.raw');
lssig(x)
vin = evalsig(x, 'in');
vout = evalsig(x, 'out');
time = evalsig(x, 'TIME');
figure(3)
plot(time*1e9,vin, 'linewidth',2);
xlim([0 20]);
hold;
plot(time*1e9,vout, 'linewidth',2);
xlim([0 20]);
set(gca, 'Fontsize',14);
title('Inverter: Transient Response');
xlabel('time (ns)');
ylabel('Voltage (V)');
legend('Vin','Vout', 'location','best');

% extract the dynamic parameters of the inverter from the TRAN curves
%
% consider:
% rise 1 of vout - slice time from 3ns to 7ns
% fall 2 of vout - slice time from 7ns to 12ns
% rise 2 of vin  - slice time from 7ns to 12 ns

idx_3 = find(time*1e9 >= 3, 1, 'first');
idx_7 = find(time*1e9 >= 7, 1, 'first');
idx_12 = find(time*1e9 >= 12, 1, 'first');
vout_rise1 = vout(idx_3:idx_7);
vout_fall2 = vout(idx_7:idx_12);
idx_per10 = find(vout_rise1 >= 0.1*Vdd, 1, 'first');
idx_per90 = find(vout_rise1 >= 0.9*Vdd, 1, 'first');
t_rise = time(idx_3+idx_per90) - time(idx_3+idx_per10);
idx_per90 = find(vout_fall2 <= 0.9*Vdd, 1, 'first');
idx_per10 = find(vout_fall2 <= 0.1*Vdd, 1, 'first');
t_fall = time(idx_7+idx_per10)-time(idx_7+idx_per90);
vin_rise2 = vin(idx_7:idx_12);
idx_vin_per50 = find(vin_rise2 >= 0.5*Vdd, 1, 'first');
idx_vout_per50 = find(vout_fall2 <= 0.5*Vdd, 1, 'first');
t_delay = time(idx_7+idx_vout_per50)-time(idx_7+idx_vin_per50);

str_trise = sprintf("t_{rise} = %.2e s", t_rise);
str_tfall = sprintf("t_{fall} = %.2e s", t_fall);
str_tdelay = sprintf("t_{delay} = %.2e s", t_delay);
text(1.5, 5.5, str_trise, 'fontsize', 14)
text(7.5, 5.5, str_tfall, 'fontsize',14)
text(13.5, 5.5, str_tdelay, 'fontsize',14)

fprintf("\nTransient parameters extracted from the TRAN curve:\n")
fprintf("\tt_rise = %.2e (s)\n", t_rise);
fprintf("\tt_fall = %.2e (s)\n", t_fall);
fprintf("\tt_delay = %.2e (s)\n", t_delay);

% Extract the dynamic parameters directly from SPICE
trise_ngsp = evalsig(x, 't_rise');
trise_SPICE = trise_ngsp(1);
tfall_ngsp = evalsig(x, 't_fall');
tfall_SPICE = tfall_ngsp(1);
tdelay_ngsp = evalsig(x, 't_delay');
tdelay_SPICE = tdelay_ngsp(1);

fprintf("\nTransient parameters extracted directly from SPICE:\n")
fprintf("\tt_rise = %.2e (s)\n", trise_SPICE);
fprintf("\tt_fall = %.2e (s)\n", tfall_SPICE);
fprintf("\tt_delay = %.2e (s)\n", tdelay_SPICE);

print(figure(1), '-dpng', 'inverter_VTC_plot.png')
print(figure(2), '-dpng', 'inverter_gain_plot.png')
print(figure(3), '-dpng', 'inverter_TRAN_plot.png')

*********************************************************
               Hspice Toolbox for Matlab
 written by Michael Perrott (http://www-mtl.mit.edu/~perrott)
   while at Silicon Laboratories (http://www.silabs.com)
     Copyright (C) 1999 by Silicon Laboratories, Inc.
     This software is distributed under the terms of
       the GNU Public License (see the COPYING file
  for more details), and comes with no warranty or support
*********************************************************


ans =

  9×9 char array

    '1:VOLTAGE'
    '2:dvout  '
    '3:in     '
    '4:out    '
    '5:vih    '
    '6:vil    '
    '7:voh    '
    '8:vol    '
    '9:vsw    '

Current plot held
VTC parameters extracted from the VTC curve:
	VSW = 2.485 (V)
	VIL = 1.966 (V)
	VIH = 2.858 (V)
	VOL = 0.5603 (V)
	VOH = 4.404 (V)
VTC parameters extracted directly from SPICE:
	VSW = 2.459 (V)
	VIL = 1.966 (V)
	VIH = 2.858 (V)
	VOL = 0.5603 (V)
	VOH = 4.404 (V)

The inverter max gain is 16.72 (V/V)
and it requires to bias the input node at: 2.472 V DC
Current plot held

ans =

  6×9 char array

    '1:TIME   '
    '2:t_delay'
    '3:t_fall '
    '4:t_rise '
    '5:in     '
    '6:out    '

Current plot held

Transient parameters extracted from the TRAN curve:
	t_rise = 2.20e-10 (s)
	t_fall = 2.10e-10 (s)
	t_delay = 4.00e-11 (s)

Transient parameters extracted directly from SPICE:
	t_rise = 2.21e-10 (s)
	t_fall = 2.06e-10 (s)
	t_delay = 3.84e-11 (s)

Published with MATLAB® R2020b